This standard stipulates the calculation method for submarines to cause large trim when on the water without relying on external conditions, relying only on the internal adjustment methods of the submarine itself. The purpose of causing a large trim is to stop sailing for maintenance of underwater components located at both ends of the submarine's orbit (such as propellers, elevator and rudder shaft bearings, torpedo launch tubes, sonar stations) and to load and unload torpedoes from the front cover of the torpedo launch tube.
CB/Z 225-1987 history
1987CB/Z 225-1987 Calculation method of large trim caused by submarine